It was in June of last year when Minnesota State Trooper Travis Pearson shot and killed 66 year old Donnie Joe Lira in front of his Cherry Township home. Lira was pointing a long gun at the trooper at the time.

Then, in August of last year, Duluth police officer Jeffrey Keast shot and killed 17 year old Joey Carl after the teen attacked the officer's squad car with a baseball bat.

In March of this year, Duluth police officer Angela Robertson shot 25 year old Samson Waddell after he reportedly assaulted her and then tried to take the weapon from her partner.

All of the officers were later cleared of any wrongdoing.

Duluth's Chief of Police, Gordon Ramsay says luckily none of the officers in these instances was severely injured.

"2010 was one of the deadliest years for police officers in decades and the first quarter of this year, the number of officers killed in the line of duty was 20 percent higher than last year."

These national statistics are of major concern to law enforcement officers, who take an oath to serve and protect. Chief Ramsey says the use of a firearm is always a last option.

Authorities say there doesn't appear to be a single factor, but the one common thread is that they are usually repeat felony level offenders.